ABSTRACT
Iru is a food flavouring condiment that is derived from fermentation of mung bean. These fermented food condiments are known to be a good source of diatery protein and vitamins. Most diets of Nigerians are lacking in fairly large amounts of protein due to the high cost of accessible protein. The high cost and inadequate supply of animal proteins and other nutrients have necessitated contemporary research, geared towards the utilization of protein from underutilized high protein legumes such as mung bean seeds. The processing steps includes, harvesting, sorting/cleaning, soaking, cooking, dehulling, with fermentation playing a significant role along the process through the activities of microorganism. The findings will be of great value to the masses by bringing to their awareness the nutritional value of iru from mung bean and soy bean. The pH, proximate, mineral, phytochemical, amino acid, volatile constituents and sensory quality of “iru” produced from dehulled and undehulled mung bean were comparatively evaluated using iru from soy bean as control. The pH showed an increase from initial 6.13 in unfermented mung bean to an alkaline pH of 7.24 and 7.67 at the end of 96 hours in iru from dehulled and undehulled mung bean. The moisture, protein, fat, flavonoid, alkaloid, tannin and phytate content of the iru samples ranged from 29.66 (dehulled mung bean) to 22.55% (control), 39.15 (control) to 25.84% (undehulled mung bean), 30.61 (control) to 14.92% (undehulled mung bean), 9.22 (undehulled mung bean) to 2.16 mg/100 g (control), 4.37(undehulled mung bean) to 1.06 mg/100 g (control), 2.13 (undehulled mung bean) to 1.05 mg/100 g (control), and 68.25 (undehulled mung bean) to 31.10 mg/100 g (control) respectively. Fifteen amino acids were detected comprising both the non-essential and the essential amino acids. Lysine, leucine, valine and phenylalanine generally had the highest amounts (5.25, 7.15, 4.18, and 5.14 g/100 g) in the iru samples as compared to other essential amino acids. Higher values were obtained for aspartic acid, arginine and glutamic acids. Thirty two volatile compounds were detected in all the iru samples. Seventeen volatile compounds were identified in iru from dehulled and undehulled mung bean respectively, while fifteen was identified in iru from soy bean. There was no significant (P>0.05) differences in the amount of each volatile compound identified in dehulled and undehulled iru from mung bean, but significant (P<0.05) different existed between iru sample from soy bean. The sensory properties showed that iru from dehulled mung bean could compete favourably well with iru from dehulled soy bean (control) in terms of consumer acceptability, whereas iru produced undehulled mung bean were the least preferred by panelist. From the result obtained from the research, it can be conclude that iru should be produced from dehulled mung bean as this will reduce the over dependence on soy bean and enhance the utilization of mung bean.
TABLE
OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgement v
Table of Contents vi
List of Tables ix
List of Figures x
List of Plates xi
Abstract xii
CHAPTER
1: INTRODUCTION
1.1
Background of the Study 1
1.2
Statement of Research Problems 2
1.3
Justification 3
1.4
Objectives of the Study 4
CHAPTER
2: LITERATURE
REVIEW
2.1 Origin and Distribution of Mung Bean 5
2.2 Nutritional and Antinutritional Composition
of Mung Bean 5
2.2.1
Nutrient composition of mung bean 6
2.2.2.
Photochemical composition of mung bean seed 7
2.3 Fermented Food Condiments 9
2.3.1
Microbiology of African Fermented Food Condiments 11
2.3.2.
Nutritional properties of fermented food condiments 14
2.4. Dawadawa/Iru: A Food Product from
Mung Bean Seeds 15
2.4.1.
Units Operation in Iru Production 18
2.4.1.1.
Sorting and Cleaning 18
2.4.12.
Soaking 18
2.4.1.3.
Dehulling 19
2.4.1.4.
Boiling 19
2.4.1.5.
Fermentation 20
2.4.2.
Other traditional fermented condiments used in Nigeria 20
2.4.2.1
Ogiri (Ricinus commnuis) Castor oil seeds 21
2.4.2.2
Ukpaka (Pentaclethra macrophylla) African oil beans 22
2.4.2.3
Okpeye (Prosopsis Africana seeds) 23
2.5.
Primary and Secondary Metabolites in Iru 23
CHAPTER
3: MATERIALS AND METHODS
3.1.
Procurements of Raw Materials and Sample Preparation 25
3.1.1.
Preparation of Iru from mung bean
(dehulled) 27
3.1.2. Preparation of Iru from mung bean (undehulled) 27
3.1.3.
Preparation of Iru from dehulled Soy
beans seed (control) 29
3.2 The pH of the Iru Samples 31
3.3 Proximate Analysis 31
3.3.1.
Determination of moisture content 31
3.3.2 Determination of crude protein 31
3.3.3.
Determination of crude fibre 32
3.3.4.
Fat content determination 33
3.3.5. Ash content determination 34
3.3.6. Carbohydrates content determination 34
3.4 Mineral Analysis 34
3.4.1.
Determination of potassium 34
3.4.2.
Determination of magnesium contents 35
3.4.3.
Determination of calcium contents 36
3.4.4.
Determination of sodium contents 37
3.4.5.
Determination of phosphorus contents 38
3.5. Phytochemical Composition of Iru 39
3.5.1 Determination of flavonoid 39
3.5.2 Determination of alkaloids 39
3.5.3. Determination of tannin 40
3.5.4. Determination of phytate 41
3.5.5.
Determination of trypsin inhibitors 42
3.6. Amino Acid Analysis 42
3.7.
Determination of Volatile Compounds 43
3.8.
Sensory Evaluation of Iru 44
3.9
Statistical Analysis 44
CHAPTER 4: RESULTS AND
DISCUSSIONS
4.1. The pH of the Iru Samples at Different Fermentation Days 45
4.3.
Proximate Content of Iru 48
4.4.
Mineral Content of the Iru 53
4.5.
Phytochemical Composition of Iru 58
4.6.
Amino Acid Profile 65
4.7.
Volatile Compounds 69
4.8.
Sensory Properties of the Iru 78
CHAPTER 5: CONCLUSION AND RECOMMENDATION
5.1
Conclusion 81
5.2.
Recommendations 82
References 83
LIST OF TABLES
4.1:
The pH values of Iru samples at
different fermentation day 46
4.2:
Proximate contents of the Iru samples
and raw mung bean seeds (%) 50
4.3:
Mineral contents of Iru samples and
raw mung bean (Mg/100 g) 55
4.4:
Phytochemical contents of Iru and raw
mung bean seeds (mg/100 g) 61
4.5:
Amino Acid content of the Iru Sample 67
4.6.
Volatile compounds identified in Iru
from mung bean 70
4.6.1: Volatile compounds identified in Iru from soy bean 71
4.7: Sensory properties
of Iru samples 80
LIST OF FIGURES
2.1: Dawadawa
production 17
3.1: Production of iru from dehulled and undehulled Mung bean seeds 28
3.2: Production of iru from soy bean seeds 30
4.1: Percentage distribution of the compounds and
total group contributions
of
volatile compounds in iru from dehulled
soybean seeds 76
4.2: Percentage distribution of the compounds and
total Group/class
contributions
of volatile compounds in iru from
dehulled and
un-dehulled
mung bean seeds 77
LIST
OF PLATES
3.1 Raw mung bean seeds 26
4.1 Iru
from dehulled Soy bean (SSD) 47
4.2 Iru
from dehulled Mung bean (MBD) 47
4.3 Iru
from undehulled Mung bean (MBU) 47
CHAPTER
1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Mung bean (Vigna
radiata) is a legume cultivated for its edible seeds and sprouts. It
belongs to the family Fabaceae and
sub family Papilionaceae with dipoid
chromosome number. There are three subgroups of Vigna radiata: one is developed (subsp Vigna radiata. radiata)
and the other two are wild (Vigna radiata
subsp. Sublobata and Vigna radiata
subsp.glabara). Mung bean is a warm seasonal annual legume, developed for
the most part as a rotational yield with grains like wheat and rice. Mung bean
is a rich source of protein and is viewed as a quality food. It constitutes an important place in vegetarian diets.
It is a rich source of dietary protein and contains higher levels of folate and
iron than most other legume (Keating et
al, 2011).
Iru
is a food seasoning used in the
preparation of soups in many African countries. They are used as soup
condiments with strong smell. It is usually employed in small proportion
in food/soup preparations. It does not only enhance the soups with proteinous
substantial taste; it likewise gives some health benefits (Oboh, 2017). It is obtained by fermenting, Soybean
seeds (Glycine max), Groundnut seeds
(Arachis hypogaea Linn) and locust
bean seeds (Parkia biglobosa).
Fermentation
is a traditional method of food processing employed to improve the nutritional,
functional, sensory properties of grains as well as their antioxidant
activities by increasing their potentials as functional foods and nutraceutical
sources (Ademiluyi and Oboh, 2011). The method utilized for iru production changes among different
ethnic groups and requires minimal capital investment (Ademiluyi and Oboh,
2011). Dehulling is an important step in iru processing involving the
removal of the seed coat called hull. These hulls are rich in bioactive
compounds and display strong antioxidant activity (Kanatt et al., 2011). The fermentation process during iru processing
however varies, usually based on human discretion, causing variations in the
final product composition.
1.2. STATEMENT OF
RESEARCH PROBLEMS
Notwithstanding
the huge nutritional values, ease of preparation and availability of local
fermented condiment from soybean seeds and locust bean seeds, there is still
need to address further the issues of exploration of other underutilized
legumes in production of condiments and development of appropriate processing
techniques to enhance functional benefits and flavour. This will go a long way
to widen the utilization of such crops, while reducing the intake of commercial
condiments which are exotic and not acceptable to some users.
Most diets of Nigerians are lacking in fairly
large amounts of protein due to the high cost of accessible protein.
The high cost and inadequate supply of animal proteins and other nutrients have
necessitated contemporary research, geared towards the utilization of protein
from underutilized high protein legumes such as mung bean seeds (Khattab
et al., 2009)
As
the lower income group of any population is particularly vulnerable to protein
calorie malnutrition, it is recommended that attention should be given to
effectively accessible, available, cheap yet nutritious plant protein, such as
mung bean to improve the nutritional status of the low-income groups of the
population (Adebo et al., 2017).
Dehulling
is a tedious process which leads to the loss of some nutrients such as tannin,
flavonoid, alkaloid and phytate that are present in the hulls. Consuming
legumes with the hulls can be useful to human as they contain antioxidants and
also add a distinctive flavour.
1.3 JUSTIFICATION
Fermented
food condiments are flavour enhancers that are added to food to impart a
particular flavour or enhance its taste. These fermented food condiments are
known to be a good source of diatery protein and vitamins. They are products
usually derived from the fermentative activities of microorganisms on vegetable
proteins of legumes or oil seeds origin (Olasupo and Odunfa, 2010). Aside from enhancing
flavouring attributes, they contribute to the protein intake of the consumers. Thus,
the use of indigenous and underutilized indigenous agricultural produce (such
as legumes) with possible functionality should be explored (Adebo et
al., 2017). As the lower income group of any
populace is particularly vulnerable to malnutrition, it is recommended that
consideration should be given to effectively accessible, available, cheap yet
nutritious plant protein, (such as mung bean) to
improve the nutritional status of the low-income groups of the population.
Thus,
various benefits will be derived from the production of iru from mung bean. The findings will be of value to the masses by
bringing to their knowledge the dietary benefit of mung bean. With the findings
from this study, the overall population of Nigeria will know the ingredient to
use for iru production regarding the
nutrients, flavour and health benefits. The result of this study will also prompt
expanded cultivating of Mung bean (Vigna
radiata) seed subsequently prompting youth empowerment.
This
work exists because of insufficient information with regards to the nutritional
and phytochemical composition of iru
from dehulled and undehulled mung bean seeds.
1.4 OBJECTIVE OF THE STUDY
The
main objective of this research work was to evaluate the nutrients and
phytochemical composition, antioxidant and sensory properties of iru prepared
from mung bean seeds.
The
Specific Objectives of this research work include:
1. Produce iru from dehulled and undehulled mung
beans.
2.
Determine the effect of fermentation duration of mung bean on the pH of iru.
3. Determine the chemical and sensory properties of
the obtained iru.
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